Governor for air-compressors



. Patented Nov. 8, I898.. S. H. LIBBY &. W. B. POTTER.

GOVERNOR FOR AIR COMPRESSORS.

(Application filed Mar. 6, 1897.) (No Model.) 2 Sheets-Shaet I.

MA H E55 E5.

GUM-

No. 6l3,692. Patented Nov. 8, i898. s. H. LIBBY & W. B. POTTER.

aovznnon' FOR AIR DDMPRESSOBS.

(Application filed Bar. 6, 1897.) (I0 Ilodal.) 2 Shasta-Sheet 2.

UNITED STATES ATENT FFICE.

SAM H. LIBBY AND VILLIAM B. POTTER, OF SCHENECTADY, NEV YORK, ASSIGNORS TO THE GENERAL ELECTRIC COMPANY, OF NEW YORK.

GOVERNOR FOR AlR-COMPRESSORS.

SPECIFICATION forming part of Letters Patent No. 613,692, dated November 8, 1898.

Application filed r h 6, 1897- Serial No. 626,259. (No model.)

To all whom, it may concern.-

Be it known that we, SAM H. LIBBY and WILLIAM B. POTTER, citizens of the United States, residing at Schenectady, in the county of Schenectady, State of New York, have invented certain new and useful Improvements in Governors for Air-Compressors, (Case No. 535,) of which the following is a specification.

The present invention relates to governors for air-compressors which are so arranged that when the air-pressure in the receivingtank rises above or falls below a certain point the air-compressor is automatically started or stopped, as the case may be.

The invention relates more particularly to governors used in connection with compressors driven by electric motors wherein a suitable contact device is arranged to make and break the motor-circuit.

One of the objects of the present invention is to provide a governor for an air-compressor in which the air-pressure of the system is directly utilized to actuate the mechanism for disconnecting the motive power from the compressor, with an auxiliary means for regulating the action of the air-pressure.

A further object of the invention is to provide a governor for an electric-motor-driven air-compressor which is so arranged that the direct air-pressure of the system is utilized to actuate the circuit controlling mechanism of the motor when it is desired to interrupt the circuit thereof, with an auxiliary means so arranged that while the air-pressure is below maximum it prevents the admission of air to the switch-actuating mechanism, but which when the pressure rises above normal opens a valve admitting air to the cylinder of the switch-actuating device.

The invention also relates to certain novel features more fully described and claimed hereinafter.

In the accompanying drawings, attached to and made a part of this specification, Figure 1 is a front elevation, partially in section, of our improved apparatus. Fig. 2 is a sectional View taken on the line 2 2. of Fig. 1. Fig. 3 is a modification of the switch mechanism, and Fig. 4: is a diagrammatic view showing the relation of the several parts.

The cast-iron base A of the governor is mounted on a support in the position shown in Fig. 1 and secured thereto by bolts entering the holes A in the base. On the upper end of the base is a coil'of wire B, which energizes the magnet for interrupting the arcs formed when the circuit is interrupted between the stationary brushes C and the movable contacts D.

Secured to the base A by a bolt E is a polepiece F, and to the latter is secured by screws an arc-deflector G, having separators G situated between the contacts D. Extending outward from the base A and forming a part of the magnetic circuit are lugs A A in which the shaft H is mounted. The contacts D are mounted on iron fingers D, also forming a part of the magnetic circuit and having hubs D D which are mounted on the shaft H, but separated therefrom by insulation.

Mounted on a piece of wood I, secured to the base A by means of screws,are the brushes C. Each brush is provided with a suitable spring to enable it to make good contact with the moving contacts D. A binding-post C is provided for each brush. The stationary brushes C, of which there are four, are connected as follows: the two outside ones to the line and the middle ones to the magnet-coil B. The moving contacts D are divided electrically into pairs, one pair being mounted on the finger D and the other pair on the finger D The relation of the contacts will be more fully described in connection with Fig. 4.

The circuit of the magnetic lines is from the core of the magnet B, the pole-piece F, to the iron fingers D, the shaft H, the lugs A A in which the shaft is mounted, and the base A to the point of starting. Any are formed by the interrupting of the circuit will be immediately destroyed by the magnet, and the separators G prevent the are from jumping from one contact D to another.

Rigidly mounted on the shaft H, between the hubs D D is a forked arm J, to which is hinged the piece J through which motion is imparted from the piston to the shaft H. Pivoted to a projection of the base is an arm K, having a roller on its outer end engaging with a flattened portion of the piece J and tending to hold it in the position shown. EX-

tending downward from the base is a pr0jeca tion in which is mounted the end of the spring K, the other end being secured to the arm K. Suitable means are provided for adjusting the tension of the spring. The arm K is prevented from moving any farther down by a projection A on the base,which engages with the under part. On the lower part of the base is formed a lug A, to which is detachably secured the pneumatic portion of the governor.

The governor is provided with a main body of cast metal M and has a flange M at the upper portion for securing it to the lug A of the base A. In the upper end is formed the main cylinder IT, in which the piston l 'is adapted to travel. The piston is provided with a suitable packing on the lower end and at its upper end with a rounded socket, into which the lower end of the piece J projects. The piece J is not secured to the piston, but merely rests in the bottom of the socket formed therein. By this construction the pneumatic part of the apparatus can be removed as a whole from the switching mechanism by simply removing the bolts M Atthe lower end is formed an auxiliary cylinder 0, in which is mounted a piston O. Secured to the lower end of the casting M by a screw-thread is a pipe P, and between the end of the pipe and the casting is a head P, to which one end of the spring P is secured. Extending through the head P is a rod Q, having 011 its lower end a screw-threaded portion upon which the nut Q is mounted. To this nut is secured the outer end of the spring P The pipe P serves to protect the rod and nut, and by holding the nut from rotating the tension of the spring can readily be changed by applying a Wrench to the squared end of the rod and retating it. 011 the inner end of the rod is a collar P and engaging therewith is the pivoted lever B. The piston O is provided with a packing to insure a good fit with the cylinder and on its lower end is provided with a socket, into which the end of the rod P projects, the latter being retained in position by the pressure of the spring P On the left side a slot is provided, through which projects the lever R. 011 the inner end of the piston is mounted a pin 0 having a slight enlargement in the lower part, forming a seat for the springs O O, which are situated above and below it. A cap 0 is employed to furnish a support for the upper end of the spring O and at the same time act as a guide for the pin. The inner end of the pin is tapered and is adapted to engage with the hole S, which forms a valve connecting the auxiliary cylinder 0 with the main cylinder N. At the left of the auxiliary cylinder and parallel with it is an exhaust-valve T, consisting of a screwthreaded piece T, in which is mounted the spring-pressed plunger T The plunger is formed with grooves in the side which con nects with the passage N leading from the main cylinder N, and a pin Tflwhich projects through the piece T and engages with an adj Listing-screw carried by the lever B. On the right side of the casting M is a screw-threaded projection U, upon whichis mounted a strainer V to prevent dirt from entering the governor from the pressure-pipe V, which is connected to the receiving-tank \V. The piston O can readily be removed by unscrewing the pipe P and removing the lever R.

In Fig. 3 is shown a modification of the invention whereby a quick make and break of the motor-circuit is obtained. The finger D is made of iron and on its upper end is provided with a contact D, which engages with the stationary brush 0. A hub is provided for the finger, which is mounted on the shaft II and is suitably insulated therefrom. Mounted on the shaft II is a piece II, upon which are mounted the pins Ct l). Between the pin CL and the base A is an auxiliary spring 0, which is arranged to work over a dead-center. The piston I works in the cylinder N, and connected thereto by a pin N is the piece J. The upper end of the piece J is provided with a slot in which the pin 1) travels. To return the piston and piece J to place, an extension-spring K is secured at one end to the casting A and at the other end to the piece J. When the piston N is forced upward, the pin Z) engages with the bottom of the slot in the piece J, and as soon as the pin a has moved to a point below the center of the shaft II the spring 0 will open the circuit between the contact D and the brush 0 with a snap. The end of piston .L striking the washer between the casting M and the flange A would limit the outward movement of the finger D.

In Fig. 4 is shown a diagrammatic view of a system to which our invention is applied. At W is represented an air-compressor of any suitable type, which is driven by the series motor X. This motor is, preferably, directly connected, but for the purpose of illustration is shown as belted.

lVe have found that series motors possess certain advantages over other types for this kind of work, for the field-winding being in series with the armature will prevent a sudden rush of current through the armature at the time the circuit is closed, and at the same time the field builds up as the current increases in the armature. \Ve prefer to dis pense with the use of auxiliary resistance in the motor-circuit, so that the motor may respond more quickly when the circuit is closed, and by using a series motor the field will act as an inductive resistance and prevent a too great rush of current until the speed of the motor increases to normal, when the counter electromotive force in the armature will regulate the flow of current.

The receiving-tank W is connected by a pipe to the compressor W and to the governor by the pressure-pipe V, which is provided with a suitable strainer V and an insulatingcoupling V. Current enters by the trolley l and passes through a part of the contacts on the switch mechanism, thence through the B of the blow-out magnet and the remaining contacts on the switch to thefield and armature of the motor X to ground. It will be seen that the fingers D D of the switch mechanism form bridges between the pairs of stationary brushes 0 and that the coil B unites the middle pair of stationary brushes. The circuit is interrupted at four points in series, which reduces the are formed at each point, so that it may readily be extinguished without damage to the contacts. If desired, an

increased number of points can be arranged at which the circuit is interrupted.

The operation of our invention will now be described. The pipe V being connected to the receiving-tank and the cylinder 0, there is, under normal conditions, a certain amount of air-pressure in the auxiliary cylinder 0 acting on the piston 0 against the pressure of the spring P. So long as the spring-pressure preponderates, the parts remain as shown and the circuit through the switch mechanism is closed and the motor drives the air-compressor. WVhen the air --pressure in the receiving-tank rises to a point where it is greater than that of the spring, the piston 0 moves downward, causing the pin 0 to be withdrawn from the valve S, the latter connecting the main and auxiliary cylinders. The arrangement of the parts is such that the piston O has a slight movement before the pin 0 opens the valve S, and a very small movement of the pin will cause a large opening of the valve, and air is freely admitted to the cylinder N, thereby causing the piston I to respond quickly and move the piece J upward and transmit motion to the shaft H, which causes the circuit between the contacts D and brushes 0 to be interrupted. The piston will remain in its upper position as long as the air-pressure is above normal, and the motor-circuit will be interrupted. 'As soon as the pressure decreases, the piston 0 moves upward and the pin 0 closes the valve S. Then the collar P engages with the lever R, moving the latter upward, causing the adjusting-screw to engage with the pin T and open the valve, which permits the air to escape from the cylinder N and allows the piston and contacts D to return to the position shown under the action of the spring K, thereby closing the motor-circuit.

The action of the modification shown in Fig.

.3 is the same as above, except that the finger D has a snap action, due to the spring 0 moving over a dead-center.

It will be seen that the governor is operated by direct air-pressure from the receiving-tank W and that the pressure is controlled by the auxiliary cylinder and piston. By this arrangement we are enabled to provide a quickacting governor and one responsive to very slight changes in the air-pressure.

' What we claim as new, and desire to secure by Letters Patent of the United States, is

1. In a pneumatic governor for air-compressors, the combination of a switch mechanism, a piston and cylinder for actuating the switch mechanism, an auxiliary piston and cylinder, a valve between the cylinders, a spring-supported pin actuated by the auxiliary piston for opening and closing the valve, a spring tending to maintain the auxiliary piston in its normal position, an exhaust-valve connecting with the switch-actuating cylinder, a spring-pressed device normally closing the exhaust-valve, and means controlled by the auxiliary piston for opening the exhaustvalve.

2. In a pneumatic governor for air-compressors, the combination of a switch mechanism mounted for oscillating movement, contacts on the switch arranged to break the circuit at a number of points simultaneously, a

spring normally maintaining the switch in a closed position, a piston and cylinder arranged to open the switch when the air-pres sure becomes too great, and auxiliary means controlling the admission of air to the cylinder.

3. In a pneumatic governor for air-compressors, the combination of switch-contacts mounted for oscillatory movement, stationary brushes engaging therewith, a main piston and cylinder operating by direct air-pressure to move the contacts in one direction, a spring to move the contacts in the opposite direction, an auxiliary spring connected to a stationary part of the base and the switch, arranged to work over a deadcenter, and an auxiliary piston and cylinder for controlling the admis sion of air to the main cylinder.

4. In a pneumatic governor for air-compressors, the combination of a switch for closing and opening an electric circuit, a main piston and cylinder for actuating the switch, an auxiliary piston and cylinder, and a valve between the main and auxiliary cylinders ac tuated by the auxiliary piston and having a movement independent thereof.

5. In a pneumatic governor for air-compressors, the combination of a switch for closing and opening an electric circuit, a main piston and cylinder for actuating the switch, an auxiliary piston and cylinder, and a springsupported valve located between the cylinders and actuated by the auxiliary piston, and means permitting a limited movement of the valve independent of the piston.

6. In a pneumatic governor for air-compressors, the combination of a base, contacts mounted upon the base for oscillating movement, a cylinder bolted to the base in which is mounted a piston for actuating the contacts, an auxiliary cylinder formed integral with the main cylinder and connected thereto by an air-passage, and a valve for closing and opening the air-passage actuated by a piston but having a limited movement independent thereof.

' 7. In a pneumatic governor for air-com pressors, the combination of a metal base, a shaft mounted in bearings upon the base, contacts carried by the shaft and adapted to cngage with stationary contacts, an arm mounted on the shaft, a piece secured to the arm, and a piston for actuating the switch having a socket in which one end of the piece is seated.

8. In a pneumatic governor for air-compressors, the combination of a switch, a main piston and cylinder for actuating the switch, an auxiliary piston and cylinder for regulating the admission of air to the main cylinder, and a spring-supported valve carried by the auxiliary piston.

9. In a pneumatic governor for air-compressors, the combination of a switch, a main piston and cylinder for operating the switch, an auxiliary piston and cylinder for regulating the admission of air to the main cylinder, a valve carried by the auxiliary piston for varying an opening between the main and auxiliary cylinders, and springs supporting the valve in such manner that it is free to move in two directions from a central position independent of the piston.

10. In a pneumatic governor for air-compressors, the combination of a switch mechanism mounted upon a metal base, main and auxiliary cylinders formed in one piece and bolted to the base in such manner that they can be removed without disturbing the switch mechanism,an opening between the cylinders, a spring-pressed valve carried by the auxiliary piston for varying the extent of said opening, an adjustable extension-spring tending to move the auxiliary piston to one end of its cylinder, and a spring-pressed exhaust-valve.

In witness whereof we have hereunto set our hands this Ith day of March, 1897.

SAM H. LIBBY. WILLIAM B. POTTER. Witnesses:

B. B. HULL, E. W. CADY. 

